What is the recommended anesthesia protocol for patients with neuromuscular disorders undergoing surgery?

Anesthesia Protocol for Patients with Neuromuscular Disorders

For patients with neuromuscular disorders, a trigger-free anesthesia avoiding succinylcholine and volatile anesthetics is strongly recommended, with mandatory neuromuscular monitoring and reduced dosing of non-depolarizing muscle relaxants. 1

Pre-anesthetic Assessment

• Identify specific type of neuromuscular disorder (myopathy, neuropathy, neuromuscular junction disorder)
• Assess baseline respiratory function (FVC particularly important - patients with FVC <50% are at increased risk, those with FVC <30% at high risk) 1
• Evaluate cardiac function (especially in muscular dystrophies)
• Check for history of rhabdomyolysis 1
• Determine baseline neuromuscular function using TOF monitoring before induction 1

Anesthetic Technique Selection

First-line approach:

• Total intravenous anesthesia (TIVA) with propofol and short-acting opioids 1
• Regional anesthesia when feasible (spinal, epidural, peripheral nerve blocks) 1

Absolutely contraindicated:

• Succinylcholine - contraindicated in all neuromuscular disorders due to risk of:
  • Hyperkalemia (in chronic motor deficits) 1
  • Rhabdomyolysis (in myopathies) 2, 3
  • Malignant hyperthermia-like reactions 4
  • Prolonged paralysis (in butyrylcholinesterase deficiency) 5

Muscle Relaxant Management

For non-depolarizing muscle relaxants:

• Myasthenia gravis patients:

  • Increased sensitivity to non-depolarizing agents
  • Reduce dose by 50-75% for atracurium/cisatracurium 1
  • Pre-induction TOF ratio <0.9 indicates greater sensitivity 1

• Primary muscle damage (e.g., muscular dystrophies):

  • Significantly increased sensitivity to rocuronium
  • Onset and recovery times significantly longer 1
  • Reduce dosing and monitor closely

• Chronic motor deficit with up-regulation of nAChRs:

  • Reduced sensitivity to non-depolarizing agents
  • May require higher doses 1

• In renal/hepatic failure:

  • Prefer benzylisoquinoline muscle relaxants (atracurium/cisatracurium) 1

Mandatory Monitoring

• Quantitative neuromuscular monitoring is essential whenever muscle relaxants are used 1
• Apply monitoring before induction and use throughout all phases of anesthesia 1
• Ulnar nerve monitoring preferred; if inaccessible, use electromyography devices 1
• Document TOF ratio ≥0.9 before extubation 1

Reversal of Neuromuscular Blockade

• Sugammadex is strongly recommended for reversal of steroidal muscle relaxants (rocuronium/vecuronium) in neuromuscular disorders 1, 6, 4

  • Dosing: 2 mg/kg at reappearance of T2, 4 mg/kg for deeper blockade 6
  • Faster recovery compared to neostigmine 6

• Avoid neostigmine when possible due to:

  • Potential interference with long-term treatment in myasthenia 1
  • Drying of secretions, rhythm disorders, and effects on muscle action potential in primary muscle damage 1

Respiratory Support

• Consider respiratory support during induction and recovery for patients with FVC <50% 1
• Strongly consider respiratory support for patients with FVC <30% 1
• Options include:
  • Manual ventilation with face/nasal mask
  • Mechanical ventilation with conventional or bilevel positive pressure ventilators 1

Extubation Strategy

• Consider direct extubation to non-invasive positive pressure ventilation (NPPV) for:
  • Patients with FVC <50% (strongly consider for FVC <30%) 1
  • Patients using NPPV preoperatively 1
• Delay extubation until respiratory secretions are well-controlled and SpO2 is normal/at baseline 1

Common Pitfalls and Caveats

• Failure to identify undiagnosed neuromuscular disease preoperatively
• Underestimating respiratory compromise in the postoperative period
• Inadequate neuromuscular monitoring leading to residual paralysis
• Using standard dosing of muscle relaxants in patients requiring reduced doses
• Relying on clinical tests of recovery (head lift, hand grip) which are inadequate 1
• Assuming safe recovery without quantitative TOF monitoring showing ratio ≥0.9 1

By following this protocol, the risk of serious complications such as prolonged neuromuscular blockade, respiratory failure, and malignant hyperthermia can be significantly reduced in patients with neuromuscular disorders undergoing surgery.